[vdr] FF card A/V sync suggestion

Udo Richter udo_richter at gmx.de
Fri Oct 20 16:05:19 CEST 2006

Tero Siironen wrote:
> However, like Pasi Juppo told earlier in other thread, in last weeks episode
> of Lost there was many fadeout-fadeins between scenes and a/v desync
> happened on every one of these.

I've 'heard of such problems' on ATV+ and Lost. Whenever there's a fade 
into black, the data stream seems to get stuck, frames get delayed, and 
as consequence A/V desyncs and playback gets jerky, with lots of audio 
and video frame drops. This can be fixed by pausing and jumping a few 
frames backwards.

My theory is that since audio is typically 600ms ahead of video, maybe 
the audio buffers run over. Strange thing is why this happens 
reproducible on blackness. Maybe due to extremely low bit rate in this 
situation, more frames get packed into one data block, causing data flow 
to be disturbed beyond some limit. It cant be too high data rate, ATV+ 
has just 2mbit avg, 4mbit max data rate.



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